Composite laminates are increasingly used in gas turbine engines, such as for structural components in the engine bypass gaspath. However, structural components made from composite laminates are subjected to erosion by airborne contaminants, such as water and hail. Composite laminates are often unpainted. Due to their uniform visual properties, it may be difficult to determine during a general visual inspection if a part is worn or is eroded beyond an acceptable service limit of the component.